The international standard, and therefore the standard used "officially" on this site, is liters. US gallons is used almost exclusively in the USA, but since the majority of the participants on this board are Americans it is frequently found in the topics here (on the rest of the site you'll mostly see liters).

That's why we have a handy converter at the bottom of every page on the site._________________Success with a fish/tank is measured in YEARS, not months or weeks...

At the moment my tank is holding 66 litres of water, I have enough room to move it up to 68 litres, my question is I have an Aqua One hang on the back 3 stage filtration system. Do I really have to allow for the waterfall effect providing bubbles and current. Or can I push up my water level removing the waterfall effect and add a bubble rod to compensate._________________Wish I had a fish room